Simulator valve and electronic brake system using the same

ABSTRACT

A simulator valve and an electronic brake system using the same are disclosed. The electronic brake system includes a master cylinder provided with at least one cylinder chamber having a volume changeable according to operation of a pedal, a pedal simulator connected to the cylinder chamber, configured to provide reaction force corresponding to a pedal effort of the pedal, a hydraulic-pressure supply device configured to provide hydraulic pressure to at least one wheel cylinder, an electronic control unit (ECU) configured to operate the hydraulic-pressure supply device, and a simulator valve provided in a flow passage through which the master cylinder is connected to the pedal simulator, and provided with a unidirectional flow passage that allows fluid to flow from the pedal simulator to the cylinder chamber and a bidirectional flow passage that is electronically opened or closed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. § 119to Korean Patent Application Nos. 2017-0127007 and 2017-0127019,respectively filed on Jul. 29, 2017 and Sep. 29, 2017 in the KoreanIntellectual Property Office, the disclosure of which is incorporated byreference in its entirety.

BACKGROUND 1. Field

Embodiments of the present disclosure relate to a simulator valve and anelectronic brake system using the same, which may generate a brakingforce using an electrical signal corresponding to a displacement of abrake pedal.

2. Description of the Related Art

A hydraulic brake system for braking of a vehicle is essentially mountedto a vehicle, and various systems have recently been proposed to obtainstronger and more stable braking force. Examples of hydraulic brakesystems include anti-lock brake systems (ABSs) to prevent slippage ofwheels during braking, brake traction control systems (BTCSs) to preventslippage of driving wheels during sudden unintended acceleration from astop or upon rapid acceleration of a vehicle, and electronic stabilitycontrol systems (ESCs) to stably maintain a driving state of vehicles bycontrolling a brake hydraulic pressure through combination of ananti-lock brake (ABS) system with a brake traction control system.

Meanwhile, in order to drive or stop a brake system of the electronicstability control system (ESC), it is necessary for a predeterminedamount of fluid to be applied to the electronic stability control system(ESC). In order to implement the ESC brake system, a plurality ofelectronically-controlled simulator valves may be mounted to a modulatorblock.

A simulator valve for use in the above-mentioned brake system generallyincludes a hollow valve housing, a hollow cylindrical sleeve, a valveseat, a magnetic core, and an armature. The hollow valve housing isinserted into a bore of a modulator block, and includes an inlet and anoutlet through which fluid or oil communicates with the modulator block.The hollow cylindrical sleeve is inserted into an upper end of the valvehousing, and is welded to the upper end of the valve housing. The valveseat is press-fitted into the valve housing, and includes an orificetherein. The magnetic core is welded to the sleeve located opposite tothe hollow valve housing. The armature may be movably received in thesleeve.

CITED REFERENCE Patent Document

Korean Patent Registration No. 10-1276072 (Jun. 18, 2013)

SUMMARY

Therefore, it is an aspect of the present disclosure to provide asimulator valve and an electronic brake system using the same, which canefficiently operate as well as to be easily manufactured at low costs.

Additional aspects of the invention will be set forth in part in thedescription which follows and, in part, will be obvious from thedescription, or may be learned by practice of the invention.

In accordance with an aspect of the present disclosure, an electronicbrake system includes a master cylinder provided with at least onecylinder chamber having a volume changeable according to operation of apedal, a pedal simulator connected to the cylinder chamber, configuredto provide reaction force corresponding to a pedal effort of the pedal,a hydraulic-pressure supply device configured to provide hydraulicpressure to at least one wheel cylinder, an electronic control unit(ECU) configured to operate the hydraulic-pressure supply device, and asimulator valve provided in a flow passage through which the mastercylinder is connected to the pedal simulator, and provided with aunidirectional flow passage that allows fluid to flow from the pedalsimulator to the cylinder chamber and a bidirectional flow passage thatis electronically opened or closed.

The unidirectional flow passage may be formed by a lip seal provided inthe simulator valve.

The simulator valve may include a sleeve, an upper part of which iscoupled to a magnet core and a lower part of which is coupled to a valvehousing provided with an orifice, an armature configured to move upwardand downward in the sleeve, a first elastic member disposed between themagnet core and the armature to provide elastic force to the armature,and a lip seal coupled to an outer surface of the valve housing, andprovided with an inclined protrusion. The unidirectional flow passage isopened, because the inclined protrusion is deformed inward when pressureof the pedal simulator is higher than pressure of the master cylinder.The bidirectional flow passage is opened, because the armature moves bythe magnet core receiving a current and the orifice is opened.

The sleeve may be press-fitted into an inner surface of the valvehousing and coupled to the valve housing by welding.

The simulator valve may include a sleeve, an upper part of which iscoupled to a magnet core and a lower part of which is coupled to the lipseal, an armature configured to move upward and downward in the sleeve,a first elastic member disposed between the magnet core and the armatureto provide elastic force to the armature, and a valve seat disposedbelow the armature and provided with an orifice to be opened or closedby the armature, and a second elastic member configured to provide thevalve seat with elastic force in a direction of the armature. Whenpressure of the pedal simulator is higher than pressure of the mastercylinder, the unidirectional flow passage is opened or closed by upwardor downward movement of the valve seat in a space between the valve seatand the sleeve, or is opened or closed by deformation of an inclinedprotrusion of the lip seal.

One end of the second elastic member may be supported by the sleeve, andthe other end of the second elastic member may pressurize the valve seatat a lower side of the valve seat.

The simulator valve may further include a stopper coupled to a modulatorblock. The sleeve may be press-fitted into an inner surface of thestopper and coupled to the stopper by welding.

The simulator valve may include a sleeve, an upper part of which iscoupled to a magnet core and a lower part of which is coupled to a valvehousing, an armature configured to move upward and downward in thesleeve, a first elastic member disposed between the magnet core and thearmature to provide elastic force to the armature, and a first valveseat disposed below the armature, and provided with an orifice to beopened or closed by the armature, a second elastic member configured toprovide the first valve seat with elastic force in a direction of thearmature, and a second valve seat fixed to the valve housing. Theunidirectional flow passage is opened or closed by upward or downwardmovement of the first valve seat in a space between the first valve seatand the second valve seat.

One end of the second elastic member may be supported by the sleeve, andthe other end of the second elastic member may pressurize the firstvalve seat at a lower side of the first valve seat.

One end of the second elastic member may be supported by the valvehousing, and the other end of the second elastic member may pressurizethe first valve seat at a lower side of the first valve seat.

The first elastic member may allow the second elastic member to havestronger force than force needed to pressurize the first valve seat suchthat the orifice remains closed in a normal state. When a current issupplied to the magnet core, the armature may move and the orifice maybe opened.

In case that pressure of the pedal simulator is higher than pressure ofthe master cylinder, if a sum of a difference in pressure between thepedal simulator and the master cylinder and force generated when thesecond elastic member pushes the first valve seat is higher than otherforce generated when the first elastic member pushes the first valveseat, the unidirectional flow passage may be opened.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects of the invention will become apparent andmore readily appreciated from the following description of theembodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a hydraulic circuit diagram illustrating a simulator valve ofa first embodiment and a non-braking state of an electronic brake systemprovided with the simulator valve.

FIG. 2 is a side cross-sectional view illustrating a simulator valveaccording to a first embodiment of the present disclosure.

FIG. 3 is a side cross-sectional view illustrating an open simulatorvalve according to a first embodiment of the present disclosure.

FIG. 4 is a side cross-sectional view illustrating a simulator valveaccording to a second embodiment of the present disclosure.

FIG. 5 is a side cross-sectional view illustrating an open simulatorvalve according to a second embodiment of the present disclosure.

FIG. 6 is a side cross-sectional view illustrating a simulator valveaccording to a third embodiment of the present disclosure.

FIG. 7 is a side cross-sectional view illustrating an open simulatorvalve according to a third embodiment of the present disclosure.

FIG. 8 is a side cross-sectional view illustrating an open simulatorvalve according to a fourth embodiment of the present disclosure.

FIG. 9 is a side cross-sectional view illustrating an open simulatorvalve according to a fourth embodiment of the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to the embodiments of the presentdisclosure, examples of which are illustrated in the accompanyingdrawings. The embodiments to be described below are provided to fullyconvey the spirit of the present disclosure to a person skilled in theart. The present disclosure is not limited to the embodiments disclosedherein and may be implemented in other forms. In the drawings, someportions not related to the description will be omitted and will not beshown in order to clearly describe the present disclosure, and also thesize of the component may be exaggerated or reduced for convenience andclarity of description.

Referring to FIG. 1, an electronic brake system 1 generally includes amaster cylinder 20 to generate hydraulic pressure, a reservoir 30coupled to an upper part of the master cylinder 20 to store oil, aninput rod 12 to apply pressure to the master cylinder 20 according to apedal effort of a brake pedal 10, one or more wheel cylinders 40 toperform braking of respective wheels RR, RL, FR, and FL when hydraulicpressure is transferred thereto, a pedal displacement sensor 11 to sensedisplacement of the brake pedal 10, and a pedal simulator 50 to providereaction force corresponding to the pedal effort of the brake pedal 10.

The master cylinder 20 may be provided with at least one chamber togenerate hydraulic pressure. For example, the master cylinder 20 may beprovided with two cylinder chambers. From among the two cylinderchambers, one cylinder chamber may be provided to a front of a secondpiston 22 a, and the other cylinder chamber may be disposed between afirst piston 21 a and the second piston 22 a. The first piston 21 a maybe coupled to the input rod 12. The master cylinder 20 may include firstand second hydraulic ports 24 a and 24 b through which hydraulicpressure is discharged outside from two cylinder chambers, respectively.

The master cylinder 20 provided with two cylinder chambers may bedesigned to secure safety in the event of malfunction. For example, onecylinder chamber from among the two cylinder chambers may be connectedto the front right wheel FR and the rear left wheel RL of a vehicle, andthe other cylinder chamber may be connected to the front left wheel FLand the rear right wheel RR. By configuring the two cylinder chambers tobe independent of each other, braking of the vehicle remains possibleeven when one of the two cylinder chambers malfunctions.

Alternatively, differently from the drawings, one of the two cylinderchambers may be connected to two front wheels FR and FL, and the othercylinder chamber may be connected to two rear wheels RR and RL. One ofthe two cylinder chambers may be connected to the front left wheel FLand the rear left wheel RL, and the other cylinder chamber may beconnected to the rear right wheel RR and the front right wheel FR. Inother words, wheels connected to the cylinder chambers of the mastercylinder 20 may be located at various positions.

A first spring 21 b may be disposed between the first piston 21 a andthe second piston 22 a of the master cylinder 20, and a second spring 22b may be disposed between the second piston 22 a and one end of themaster cylinder 20.

The first spring 21 b may be contained in one of two cylinder chambers,and the second spring 22 b may be contained in the other cylinderchamber. The first spring 21 b and the second spring 22 b may becompressed by the first piston 21 a and the second piston 22 a that movein response to change of displacement of the brake pedal 10, so that thefirst spring 21 b and the second spring 22 b may store elastic forcegenerated by compression thereof. When force pushing the first piston 21a becomes weaker than the elastic force, the elastic force stored in thefirst and second springs 21 b and 22 b may push the first and secondpistons 21 a and 22 a back to original positions thereof.

Meanwhile, the input rod 12 to pressurize the first piston 21 a of themaster cylinder 20 may closely contact the first piston 21 a. Therefore,the brake pedal 10 may directly pressurize the master cylinder 20without a pedal free stroke region, when the brake pedal 10 isdepressed.

The pedal simulator 50 may be connected to a first backup passage 251 soas to provide reaction force corresponding to a pedal effort of thebrake pedal 10. The simulation device 50 may provide reaction force tocompensate for the pedal effort of the brake pedal 10 depressed by thedriver, such that braking force can be precisely adjusted as intended bythe driver.

Referring to FIG. 1, the pedal simulator 50 may include a simulationchamber 51 to store oil discharged from a first hydraulic port 24 a ofthe master cylinder 20, a reaction force piston 52 provided in thesimulation chamber 51, a pedal simulator provided with a reaction forcespring 53 elastically supporting the reaction force piston 52, and asimulation chamber 51. The reaction force piston 52 and the reactionforce spring 53 may be installed to have a predetermined range ofdisplacement within the simulation chamber 51 by oil flowing into thesimulation chamber 51.

The reaction force spring 53 is merely an example capable of supplyingelastic force to the reaction force piston 52, and may be implemented asany of other examples capable of storing elastic force by shapedeformation therein. For example, the reaction force spring 53 may beformed of a material such as rubber, or may include various membersformed in a coil or plate shape to store elastic force therein.

A normally closed (NC) simulator valve 1300 having a check valvefunction, that remains closed in a normal state, may be disposed betweenthe pedal simulator 50 and the master cylinder 20. The simulator valve1300 may act as a check valve for allowing fluid or oil to flow in onlyone direction from the pedal simulator 50 to the master cylinder 20, andmay open an orifice by electrical operation such that fluid or oil canflow in two directions. The simulator valve 1300 will hereinafter bedescribed with reference to FIG. 2.

Several reservoirs 30 may be shown in FIG. 2, and the respectivereservoirs 30 may be denoted by the same reference number. However, thereservoirs 30 may be implemented as the same or different components.For example, the reservoir 30 connected to the pedal simulator 50 may beidentical to the reservoir 30 connected to the master cylinder 20, ormay store oil therein in a different way from the reservoir 30 connectedto the master cylinder 20.

The pedal simulator 50 may operate as follows. If a pedal effort isapplied to the brake pedal 10 by the driver of the vehicle, oil storedin the simulation chamber 51 may flow into the reservoir 20 via thesimulator valve 54 when the reaction force piston 52 compresses thereaction force spring 53, resulting in formation of proper pedal feelfor the driver. In contrast, if the driver takes a foot off the brakepedal 10 to release the pedal effort applied to the brake pedal 10, thereaction force spring 53 pushes the reaction force piston 52 such thatthe reaction force piston 52 may move back to an original positionthereof by elastic force of the reaction force spring 53. In addition,oil stored in the reservoir 30 may flow into the simulation chamber 51,such that the simulation chamber 51 may be fully filled with oil.

As described above, since the simulation chamber 51 is always filledwith oil, frictional force of the reaction force piston 52 is minimizedduring operation of the pedal simulator 50, such that durability of thepedal simulator 50 can be improved and foreign materials from theoutside can be prevented from flowing into the pedal simulator 50.

The electric brake system 1 according to the embodiment of the presentdisclosure may include a hydraulic-pressure supply device 100, ahydraulic control unit 200, a first cut valve 261, a second cut valve262, and an electronic control unit (ECU) (not shown). Thehydraulic-pressure supply device 100 may mechanically operate byreceiving an electric signal indicating the driver's braking intentionfrom the pedal displacement sensor 11 sensing displacement of the brakepedal 10. The hydraulic-pressure control unit 200 may include first andsecond hydraulic circuits 201 and 202, each of which includes two wheels(two of RR, RL, FR, FL) and controls flow of hydraulic pressure suppliedto the wheel cylinder 40 disposed in the two wheels (two of RR, RL, FR,FL). The first cut valve 261 may be disposed in a first backup passage251 configured to interconnect the first hydraulic port 24 a and thefirst hydraulic circuit 201, and may control flow of hydraulic pressure.The second cut valve 262 may be disposed in a second backup passage 252configured to interconnect the second hydraulic port 24 b and the secondhydraulic circuit 202, and may control flow of hydraulic pressure. TheECU may control the hydraulic-pressure supply device 100 and valves 60,221 a, 221 b, 221 c, 221 d, 222 a, 222 b, 222 c, 222 d, 233, 235, 236,243, and 1300 based on hydraulic pressure information and pedaldisplacement information.

The hydraulic-pressure supply device 100 may include ahydraulic-pressure providing unit 110 to provide oil pressure to besupplied to wheel cylinders, a motor to produce rotational forceaccording to an electrical signal from the pedal displacement sensor 11,and a power switching unit 130 to convert rotational motion of a motor120 into rectilinear motion and to provide the rectilinear motion to thehydraulic-pressure providing unit 110. Alternatively, thehydraulic-pressure providing unit 110 may operate by pressure suppliedfrom a high-pressure accumulator, instead of by driving force suppliedfrom the motor 120.

The hydraulic-pressure providing unit 110 may include a cylinder block111, a hydraulic piston 114, one or more sealing members 115, and adrive shaft 133. The cylinder block 111 may have a pressure chamber tostore oil supplied thereto. The hydraulic piston 114 may be provided inthe cylinder block 111. The sealing member 115 may be disposed betweenthe hydraulic piston 114 and the cylinder block 111 to seal the pressurechamber. The drive shaft 133 may be connected to the rear end of thehydraulic piston 114 to transfer power from the power switching unit 130to the hydraulic piston 114.

The pressure chamber may include a first pressure chamber 112 located ata front side (i.e., a forward direction, see a left side of FIG. 2) ofthe hydraulic piston 114, and a second pressure chamber 113 located at arear side (i.e., a backward direction, see a right side of FIG. 2) ofthe hydraulic piston 114. That is, the first pressure chamber 112 may bedivided by the cylinder block 111 and the front end of the hydraulicpiston 114, and may have a volume changeable according to movement ofthe hydraulic piston 114. The second pressure chamber 113 may be dividedby the cylinder block 111 and the rear end of hydraulic piston 114, andmay have a volume changeable according to movement of the hydraulicpiston 114.

The pressure chambers 112 and 113 may be connected to the firsthydraulic passage 211 and the fourth hydraulic chamber 214,respectively. The first hydraulic passage 211 may connect the firstpressure chamber 112 to the first and second hydraulic circuits 201 and202. The first hydraulic passage 211 may be divided into a secondhydraulic passage 212 communicating with the first hydraulic circuit 201and a third hydraulic passage 213 communicating with the secondhydraulic circuit 202. The fourth hydraulic passage 214 may connect thesecond pressure chamber 113 to the first and second hydraulic circuits201 and 202. The fourth hydraulic passage 214 may be divided into afifth hydraulic passage 215 and a sixth hydraulic passage 216.

The sealing member 115 may be disposed between the hydraulic piston 114and the cylinder block 111 to seal a gap between the first pressurechamber 112 and the second pressure chamber 113. Hydraulic pressure ornegative pressure of the first pressure chamber 112 affected by forwardor backward movement of the hydraulic piston 114 may be blocked by thepiston sealing member 115, so that the resultant hydraulic pressure ornegative pressure of the first pressure chamber 112 can be transmittedto the first and fourth hydraulic passages 211 and 214 without leakingto the second pressure chamber 113.

The first pressure chamber 112 may be connected to the reservoir 30through a first dump passage 116, such that the first pressure chamber112 may receive oil from the reservoir 30 and store the received oil ormay transmit oil of the first pressure chamber 112 to the reservoir 30.The second pressure chamber 113 may be connected to the reservoir 30through a second dump passage 117, such that the second pressure chamber113 may receive oil from the reservoir 30 and store the received oil ormay transmit oil of the second pressure chamber 113 to the reservoir 30.For example, the dump passages 116 and 117 may include a first dumppassage 116 that is branched from the first pressure chamber 112 andconnected to the reservoir 30, and a second dump passage 117 that isbranched from the second pressure chamber 113 and connected to thereservoir 30.

The second hydraulic passage 212 may communicate with the firsthydraulic circuit 201, and the second hydraulic passage 213 maycommunicate with the second hydraulic circuit 202. Therefore, hydraulicpressure may be transmitted to the first and second hydraulic circuits201 and 202 by forward movement of the hydraulic piston 114.

The electronic brake system 1 according to the embodiment of the presentdisclosure may include a first control valve 231 that is provided in thesecond hydraulic passage 212 to control flow of oil, and a secondcontrol valve 232 that is provided in the third hydraulic passage 213 tocontrol flow of oil.

The first or second control valve 231 or 232 may be implemented as acheck valve that allows oil to flow from the first pressure chamber 112to the first or second hydraulic circuit 201 or 202 and prevents oilfrom flowing from the first or second hydraulic circuit 201 or 202 tothe first pressure chamber 112. That is, the first or second controlvalve 231 or 232 may allow hydraulic pressure of the first pressurechamber 112 to flow into the first or second hydraulic circuit 201 or202, and may prevent hydraulic pressure of the first or second hydrauliccircuit 201 or 202 from leaking to the first pressure chamber 112through the second or third hydraulic passage 212 or 213.

The electronic brake system 1 may include a third control valve 233provided in the fifth hydraulic passage 215 to control flow of oil, anda fourth control valve 234 provided in the sixth hydraulic passage 216to control flow of oil.

The third control valve 233 may be implemented as a bidirectionalcontrol valve to control bidirectional flow of oil between the secondpressure chamber 113 and the first hydraulic circuit 201. The thirdcontrol valve 233 may be implemented as a normally closed (NC) solenoidvalve that remains closed in a normal state and then opened uponreceiving an opening signal from the ECU.

The fourth control valve 234 may be arranged parallel to the thirdcontrol valve 233, such that the fourth control valve may be implementedas a check valve that allows oil to flow from the second pressurechamber 113 to the first hydraulic circuit 201 and prevents oil fromflowing from the first hydraulic circuit 201 to the second pressurechamber 113.

The electronic brake system 1 according to the embodiment of the presentdisclosure may include a fifth control valve 235 provided in the seventhhydraulic passage 217 interconnecting the second hydraulic passage 212and the third hydraulic passage 213 so as to control flow of oil, and asixth control valve 236 provided in the eighth hydraulic passage 218interconnecting the second hydraulic passage 212 and the seventhhydraulic passage 217 so as to control flow of oil.

The fifth control valve 235 and the sixth control valve 236 may beimplemented as normally closed (NC) solenoid valves that remain closedin a normal state and then opened upon receiving an opening signal fromthe ECU.

When the first control valve 231 or the second control valve 232abnormally operates, the fifth control valve 235 and the sixth controlvalve 236 are opened such that hydraulic pressure of the first pressurechamber 112 can flow into the first hydraulic circuit 201 and the secondhydraulic circuit 202.

The fifth control valve 235 and the sixth control valve 236 may beopened when hydraulic pressure of the wheel cylinder 40 flows into thefirst pressure chamber 112, because the first control valve 231 providedin the second hydraulic passage 212 and the second control valveprovided in the third hydraulic passage 213 are implemented as checkvalves for allowing oil to flow only in one direction.

The electronic brake system 1 according to the embodiment of the presentdisclosure may include a first dump valve 241 provided in the first dumppassage 116 to control flow of oil, and a second dump valve 242 providedin the second dump passage 117 to control flow of oil. The first dumpvalve 241 may be implemented as a check valve that allows oil to flowfrom the reservoir 30 to the first pressure chamber 112 and prevents oilfrom flowing from the first pressure chamber 112 to the reservoir 30.The second dump valve 242 may be implemented as a check valve thatallows oil to flow from the reservoir 30 to the second pressure chamber113 and prevents oil from flowing from the second pressure chamber 113to the reservoir 30.

The second dump passage 117 may include a bypass passage. A third dumppassage 243 to control flow of oil between the second pressure chamber113 and the reservoir 30 may be provided in the bypass passage.

The third dump valve 243 may be implemented as a bidirectional solenoidvalve to control bidirectional flow of oil. The third dump valve 243 maybe implemented as a normally opened (NO) solenoid valve that remainsopened in a normal state and the closed upon receiving a closing signalfrom the ECU.

The hydraulic-pressure providing unit 110 may operate in a double-actingmanner. That is, hydraulic pressure produced in the first pressurechamber 112 by forward movement of the hydraulic piston 114 may betransmitted to the first hydraulic circuit 201 through the firsthydraulic passage 211 and the second hydraulic passage 212, therebyoperating the wheel cylinders 40 installed in the front right wheel FRand the rear left wheel RL. In addition, hydraulic pressure produced inthe first pressure chamber 112 by forward movement of the hydraulicpiston 114 may be transmitted to the second hydraulic circuit 202through the first hydraulic passage 211 and the third hydraulic passage213, thereby operating the wheel cylinders 40 installed in the rearright wheel RR and the front left wheel FL.

Negative pressure produced in the first pressure chamber 112 by backwardmovement of the hydraulic piston 114 may suction oil from the wheelcylinders 40 installed in the front right wheel FR and the rear leftwheel RL, and may transmit the suctioned oil to the first pressurechamber 112. In addition, the negative pressure produced in the firstpressure chamber 112 by backward movement of the hydraulic piston 114may suction oil from the wheel cylinder 40 installed in the rear rightwheel RR and the front left wheel FL, and may transmit the suctioned oilto the first pressure chamber 112.

The motor 120 and the power switching unit 130 of the hydraulic-pressuresupply device 100 will hereinafter be described.

The motor 120 may produce rotational force according to an output signalof the ECU (not shown), and may produce rotational force in a forward orbackward direction. A rotational angular speed and a rotation angle ofthe motor 120 may be precisely controlled. The motor 120 is well knownto those skilled in the art, and as such a detailed description thereofwill herein be omitted for convenience of description.

The ECU may control the motor 120 and valves 60, 221 a, 221 b, 221 c,221 d, 222 a, 222 b, 222 c, 222 d, 233, 235, 236, 243, and 1300 includedin the electronic brake system 1 to be described later.

Driving force of the motor 120 may generate displacement of thehydraulic piston 114 through the power switching unit 130. Hydraulicpressure generated by the hydraulic piston 114 slidably moving withinthe pressure chamber may be transmitted to the wheel cylinders 40respectively installed at the wheels RR, RL, FR, and FL through thefirst and second hydraulic passages 211 and 212.

The power switching unit 130 may convert rotational force intorectilinear movement. For example, the power switching unit 130 mayinclude a worm shaft 131, a worm wheel 132, and a drive shaft 133.

The worm shaft 131 may be integrated with a rotational shaft of themotor 120. At least one worm may be formed at the outer circumference ofthe worm shaft 131 in a manner that the worm shaft 131 is meshed withthe worm wheel 132 so that the worm wheel 132 can rotate. The worm wheel132 may be meshed with the drive shaft 133 so that the drive shaft 133performs rectilinear motion. The drive shaft 133 is connected to thehydraulic piston 114, such that the hydraulic piston 114 may slidablymove within the cylinder block 111.

In more detail, a signal sensed by the pedal displacement sensor 11 dueto displacement of the brake pedal 10 may be transmitted to the ECU (notshown), and the ECU may operate the motor 120 in one direction so thatthe worm shaft 131 may also rotate in one direction. Rotational force ofthe worm shaft 131 may be transmitted to the drive shaft 133 through theworm wheel 132, and the hydraulic piston 114 connected to the driveshaft 133 moves forward, so that hydraulic pressure occurs in the firstpressure chamber 112.

In contrast, when a pedal effort is removed from the brake pedal 10, theECU may operate the motor 120 in an opposite direction so that the wormshaft 131 may also rotate in the opposite direction. Accordingly, theworm wheel 132 may also rotate in the opposite direction, and thehydraulic piston 114 connected to the drive shaft 133 moves back to theoriginal position thereof (by backward movement), thereby generatingnegative pressure in the first pressure chamber 112. As described above,the hydraulic-pressure supply device 100 may transmit or suctionhydraulic pressure to or from the wheel cylinders 40 according to arotation direction of rotational force produced by the motor 120.

Meanwhile, when the motor 120 rotates in one direction, hydraulicpressure may occur in the first pressure chamber 112 or negativepressure may occur in the second pressure chamber 113. Information as towhether to brake the vehicle using hydraulic pressure or information asto whether to release braking using negative pressure may be determinedby controlling valves 60, 221 a, 221 b, 221 c, 221 d, 222 a, 222 b, 222c, 222 d, 233, 235, 236, 243, and 1300.

The power switching unit 130 may also be formed of a ball-screw-nutassembly. For example, the power switching unit 130 may include a screwthat is integrated with a rotational shaft of the motor 120 or rotateswith the rotational shaft of the motor 120, and a ball nut that isscrew-coupled to the screw in a restricted rotation state and performsrectilinear motion according to rotation of the screw. The hydraulicpiston 114 may be connected to the ball nut of the power switching unit130, and may pressurize the pressure chamber by rectilinear movement ofthe ball nut. The above-mentioned ball-screw-nut assembly to convertrotational force into rectilinear motion is well known to those skilledin the art, and as such a detailed description thereof will herein beomitted.

The electronic brake system 1 according to the embodiment of the presentdisclosure may further include a first backup passage 251 and a secondbackup passage 252, each of which is configured to directly transmit oildischarged from the master cylinder 20 to the wheel cylinders 40 duringabnormal operation of the electronic brake system 1. The first backuppassage 251 may be provided with the first cut valve 261 for controllingflow of oil, and the second backup passage 252 may be provided with thesecond cut valve 262 for controlling flow of oil. The first backuppassage 251 may connect the first hydraulic port 24 a to the firsthydraulic circuit 201, and the second backup passage 252 may connect thesecond hydraulic port 24 b to the second hydraulic circuit 202.

The first and second cut valves 261 and 262 may be implemented asnormally opened (NO) solenoid valves that remain opened in a normalstate and then closed upon receiving a closing signal from the ECU.

The hydraulic control unit 200 may include a first hydraulic circuit 201to control two wheels upon receiving hydraulic pressure, and a secondhydraulic circuit 202 to control the two other wheels upon receivinghydraulic pressure. For example, the first hydraulic circuit 201 maycontrol the front right wheel FR and the rear left wheel RL. The secondhydraulic circuit 202 may control the front left wheel FL and the rearright wheel RR. The wheel cylinders 40 may be respectively installed inthe four wheels FR, FL, RR, and RL, such that the wheel cylinders 40 mayreceive hydraulic pressure from the hydraulic-pressure supply device100, resulting in braking of the vehicle.

The first and second hydraulic circuits 201 and 202 may include aplurality of inlet valves 221 (221 a, 221 b, 221 c, 221 d) to controlflow of hydraulic pressure. The first hydraulic circuit 201 may beprovided with two inlet valves 221 a and 221 b connected to the firsthydraulic passage 211 such that the two inlet valves 221 a and 221 b mayrespectively control hydraulic pressures applied to two wheel cylinders40. The second hydraulic circuit 202 may be provided with two inletvalves 221 c and 221 d connected to the second hydraulic passage 212such that the two inlet valves 221 c and 221 d may respectively controlhydraulic pressures applied to the wheel cylinders 40.

In this case, the inlet valves 221 may be arranged upstream of the wheelcylinders 40. The inlet valves 221 may be implemented as normally opened(NO) solenoid valves that remain opened in a normal state and thenclosed upon receiving a closing signal from the ECU.

The first and second hydraulic circuits 201 and 202 may include checkvalves 223 a, 223 b, 223 c, and 223 d provided in bypass passages bywhich front ends and rear ends of the respective inlet valves 221 a, 221b, 221 c, and 221 d are connected to each other. The check valves 223 a,223 b, 223 c, and 223 d may allow oil to flow from the wheel cylinders40 to the hydraulic-pressure providing unit 110 and prevents oil fromflowing from the hydraulic-pressure providing unit 110 to the wheelcylinders 40. The check valves 223 a, 223 b, 223 c, and 223 d may allowbrake pressure of the wheel cylinders 40 to be rapidly discharged.Alternatively, during abnormal operation of the inlet valves 221 a, 221b, 221 c, and 221 d, the check valves 223 a, 223 b, 223 c, and 223 d mayallow hydraulic pressure of the wheel cylinders 40 to flow into thehydraulic-pressure providing unit 110.

The first and second hydraulic circuits 201 and 202 may further includea plurality of outlet valves 222 (222 a, 222 b, 222 c, 222 d) connectedto the reservoir 30 so as to improve performance or throughput whenbraking is released. The outlet valves 222 may be respectively connectedto the wheel cylinders 40 so as to control hydraulic pressure dischargedfrom the respective wheels RR, RL, FR, and FL. That is, the outletvalves 222 may sense brake pressures of the respective wheels RR, RL,FR, and FL. If decompression braking is needed, the outlet valves 222may be selectively opened to control pressure.

The outlet valves 222 may be implemented as normally closed (NC)solenoid valves that remain closed in a normal state and then openedupon receiving an opening signal from the ECU.

The hydraulic control unit 200 may be connected to the backup passages251 and 252. For example, the first hydraulic circuit 201 may beconnected to the first backup passage 251 so as to receive hydraulicpressure from the master cylinder 20, and the second hydraulic circuit202 may be connected to the second backup passage 252 so as to receivehydraulic pressure from the master cylinder 20.

The first backup passage 251 may be linked to the first hydrauliccircuit 201 at upstream sides of the first and second inlet valves 221 aand 221 b. Likewise, the second backup passage 252 may be linked to thesecond hydraulic circuit 202 at upstream sides of the third and fourthinlet valves 221 c and 221 d. Therefore, hydraulic pressure suppliedfrom the hydraulic-pressure providing unit 110 when the first and secondcut valves 261 and 262 are closed may be supplied to the wheel cylinders40 through the first and second hydraulic circuits 201 and 202.Hydraulic pressure supplied from the master cylinder 20 when the firstand second cut valves 261 and 262 are opened may be supplied to thewheel cylinders 40 through the first and second backup passages 251 and252. In this case, the plurality of inlet valves 221 a, 221 b, 221 c,and 221 d remain opened, so that operation states of the inlet valves221 a, 221 b, 221 c, and 221 d need not be changed.

Meanwhile, reference numeral ‘PS1’ not illustrated is ahydraulic-passage pressure sensor to sense hydraulic pressure of thehydraulic circuit 201 or 202. Reference numeral ‘PS2’ not illustrated isa backup-passage pressure sensor to measure oil pressure of the mastercylinder 20, and reference numeral ‘MPS’ not illustrated is a motorcontrol sensor to control either a rotation angle of the motor 120 or acurrent of the motor 120.

FIG. 2 is a side cross-sectional view illustrating a normal state of asimulator valve for an electronic brake system according to a firstembodiment of the present disclosure. FIG. 3 is a side cross-sectionalview illustrating an open simulator valve according to the firstembodiment of the present disclosure. Referring to FIGS. 2 and 3, thesimulator valve 1300 according to the first embodiment may be providedin a flow passage that connects the master cylinder 20 to the pedalsimulator 50, and may include not only a unidirectional flow passage (B)that allows flow of fluid or oil in the direction from the pedalsimulator 50 to the cylinder chamber, but also a bidirectional flowpassage (0) to be electronically opened or closed. The unidirectionalflow passage (B) may be formed by a lip seal 1380 provided in thesimulator valve 1300.

The simulator valve 1300 may include a sleeve 1320, an armature 1350, anelastic member 1340, and a lip seal 1380. A magnet core 1330 may befastened to an upper part of the sleeve 1320, and a valve housing 1310provided with an orifice 1310 may be fastened to a lower part of thesleeve 1320. The armature 1350 may move upward and downward in thesleeve 1320. The elastic member 1340 may be disposed between the magnetcore 1330 and the armature 1350, and may provide elastic force to thearmature 1350. The lip seal 1380 may be fastened to an outer surface ofthe valve housing 1310, and may include an inclined protrusion 1380 a.In the unidirectional flow passage (B), if pressure of the pedalsimulator 50 is higher than pressure of the master cylinder 20, theinclined protrusion 1380 a is deformed inward such that theunidirectional flow passage (B) may be opened. In the bidirectional flowpassage (0), if a current is supplied to the magnet core 1330, thearmature 1350 moves such that an orifice 1310 a may be opened.

The simulator valve 1300 may open or close the flow passage using thearmature 1350 moving up and down by the magnet core 1330, such that thesimulator valve 1300 may control the amount of fluid (or oil) flowing inthe bidirectional flow passage (0) for interconnecting a first port 130Aand a second port 130B. In this case, the first port 130A may beprovided in the vicinity of the master cylinder 20, and the second port130B may be provided in the vicinity of the pedal simulator 50.

The valve housing 1310 may be embedded in a bore of a modulator block1301. The modulator block 1301 may be formed as a rectangular block inwhich not only the simulator valve 1300 but also the above-mentionedconstituent elements of the electronic brake system are embeddedcompactly and densely.

The sleeve 1320 may be coupled to the valve housing 1310, and the magnetcore 1330 may be installed at an upper side of the sleeve 1320. Thesleeve 1320 may accommodate the armature 1350 therein, and may restricthorizontal movement of the armature 1350 in a manner that the armature1350 can move upward and downward only in a longitudinal direction. Inthis case, the sleeve 1320 may be press-fitted into the valve housing1310 and coupled to the valve housing 1310 by welding.

The magnet core 1330 may be press-fitted into the upper side of thesleeve 1320, such that the open upper end of the sleeve 1320 is closed.Although not shown in the drawings, a coupling groove may be formed inthe magnet core 1330, and the magnet core 1330 may be pressed to allowthe sleeve 1320 to be caught in the coupling groove, such that themagnet core 1330 and the sleeve 1320 can be more closely and tightlycoupled to each other. The above-mentioned coupling structure canfacilitate coupling between the sleeve 1320 and the magnet core 1330while simultaneously simplifying a coupling process, as compared to thewelding coupling scheme.

The armature 1350 may be installed to move upward and downward in thesleeve 1320, and a ball may be coupled to a lower end of the armature1350 so that the armature 1350 may be in contact with the valve housing1310 having the orifice 1310 a. An upper groove of the armature 1350 maybe arranged to face the magnet core 1330, resulting in formation of aspace in which the first elastic member 1340 is inserted to be describedlater.

One end of the first elastic member 1340 may be in contact with theupper groove of the armature 1350, and the other end of the firstelastic member 1340 may be in contact with the magnet core 1330. Thefirst elastic member 1340 may apply elastic force to the armature 1350so that the simulator valve 1300 may remain closed in a normal state.When magnetic force does not occur in the magnet core 1330 in a normalstate, the armature 1350 remains pressed downward by the first elasticmember 1340. When the magnet core 1330 produces magnetic force, thearmature 1350 moves upward so that the bidirectional flow passage (0) isopened through the orifice 1310 a.

The lip seal 1380 may be fastened to the outer circumference of thevalve housing 1310, and may include an inclined protrusion 1380 adeformed by a pressure difference such that fluid or oil can flow onlyin one direction. When pressure of the second port 130B is higher thanpressure of the first port 130A, the inclined protrusion 1380 a iscurved in a gap-reducing direction, such that the unidirectional flowpassage (B) is opened. In contrast, when pressure of the first port 130Ais lower than pressure of the second port 130B, the inclined protrusion1380 a is curved in a gap-increasing direction, such that theunidirectional flow passage (B) is closed.

A filter member 1390 may include a mesh portion provided at the surfacefacing the first port 130A, and may be installed at the outer surface ofthe valve housing 1310. The filter member 1390 may prevent inflow oroutflow of foreign materials contained in the operating fluid flowingthrough the bidirectional or unidirectional flow passage (0 or B).

The simulator valve 1300 including the above-mentioned constituentelements may include the bidirectional flow passage (0) formed when thearmature 1350 moves upward by operation of the magnet core 1330, and theunidirectional flow passage (B) provided between the lip seal 1380 andthe modulator block 1301. In this case, the bidirectional flow passage(0) may be opened by operation of the magnet core 1330. The inclinedprotrusion 1380 a is deformed inward only when pressure of the simulator50 is higher than pressure of the master cylinder 20 in theunidirectional flow passage (B), such that the unidirectional flowpassage (B) may be restrictively opened. As a result, when the amount offluid (or oil) flowing from the simulator 50 to the master cylinder 20is instantaneously increased, the width of the flow passage may beincreased in response to the increased amount of fluid.

FIG. 4 is a side cross-sectional view illustrating a simulator valveaccording to a second embodiment of the present disclosure. FIG. 5 is aside cross-sectional view illustrating an open simulator valve accordingto a second embodiment of the present disclosure. Referring to FIGS. 4and 5, the simulator valve 1400 for the electronic brake systemaccording to the second embodiment may include a sleeve 1420, anarmature 1450, a first elastic member 1440, a valve seat 1460, a secondelastic member 1470, a lip seal 1480, and a filter member 1490. Thesleeve 1420 may guide upward or downward movement of the armature 1450.A magnet core 1430 may be fastened to an upper part of the sleeve 1420,and a lip seal 1480 may be fastened to a lower part of the sleeve 1420.The armature 1450 may move upward and downward in the sleeve 1320. Thefirst elastic member 1440 may be disposed between the magnet core 1430and the armature 1450, and may provide elastic force to the armature1450. The valve seat 1460 may be located below the armature 1450, andmay have an orifice 1460 a to be opened or closed by the armature 1450.The second elastic member 1470 may provide the valve seat 1460 withelastic force in the direction of the armature 1450. The filter member1490 may filter out foreign materials. If pressure of the pedalsimulator 50 is higher than pressure of the master cylinder 20, theunidirectional flow passage (B) may be opened or closed by upward ordownward movement of the valve seat 1460 in a space between the valveseat 1460 and the sleeve 1420, or may be opened or closed by deformationof the inclined protrusion 1480 a of the lip seal 1480.

A stopper 1410 may be a means for fastening the simulator valve 1400 tothe modulator block 1301. The sleeve 1420 may be press-fitted into thestopper 1410 and coupled to the stopper 1410 by welding.

The valve seat 1460 may be disposed between the armature 1450 and alower stepped portion of the sleeve 1420, and may include an orifice1460 a that is opened or closed by the armature 1450 at the lower partof the armature 1450. In this case, one end of the second elastic member1470 may be supported by a curved part of a lower end of the sleeve1420, and the other end of the second elastic member 1470 may provideelastic force by pressurizing the valve seat 1460.

The unidirectional flow passage (B) may include a first unidirectionalflow passage (B) formed by deformation of the inclined protrusion 1480 aof the lip seal 1480, and a second unidirectional flow passage (B)disposed between the valve seat 1460 and the sleeve 1420. Here, in thesecond unidirectional flow passage (B), under the condition thatpressure of the pedal simulator 50 is higher than pressure of the mastercylinder 20, if the sum of a difference in pressure between the pedalsimulator 50 and the master cylinder 20 and force generated when thesecond elastic member 1470 pushes the armature 1450 is higher than forcegenerated when the first elastic member 1440 pushes the armature 1450,the second unidirectional flow passage (B) may be opened.

FIG. 6 is a side cross-sectional view illustrating a simulator valveaccording to a third embodiment of the present disclosure. FIG. 7 is aside cross-sectional view illustrating an open simulator valve accordingto a third embodiment of the present disclosure. Referring to FIGS. 6and 7, the simulator valve 2300 for the electronic brake systemaccording to the third embodiment may include a sleeve 2320, an armature2350, a first elastic member 2340, a first valve seat 2360, a secondelastic member 2370, and a second elastic member 2370. A magnet core2330 may be fastened to an upper part of the sleeve 2320, and a valvehousing 2310 may be fastened to a lower part of the sleeve 2320. Thearmature 2350 may move upward and downward in the sleeve 2320. The firstelastic member 2340 may be disposed between the magnet core 2330 and thearmature 2350, and may provide elastic force to the armature 2350. Thevalve seat 2360 may be located below the armature 2350, and may have anorifice 2360 a to be opened or closed by the armature 2350. The secondelastic member 2370 may provide the first valve seat 2360 with elasticforce in the direction of the armature 2350. The second valve seat 2380may be fixed to the valve housing 2310. The unidirectional flow passage(B) may be opened or closed by upward or downward movement of the firstvalve seat 2360 disposed between the first valve seat 2360 and thesecond valve seat 2380.

The simulator valve 2300 may include a first opening 2300A locatedadjacent to the master cylinder 20 and a second opening 2300B locatedadjacent to the pedal simulator 50. The simulator valve 2300 may open orclose the flow passage using the armature 2350 configured to move upwardand downward by the magnet core 2330, and may control the amount offluid (or oil) flowing in the bidirectional flow passage (0) throughwhich the first port 230A is connected to the second opening 2300B andthe second port 230B after passing through the first opening 2300A. Inthis case, the first port 230A may be provided at the side of the mastercylinder 20, and the second port 230B may be provided at the side of thepedal simulator 50.

The valve housing 2310 may be embedded in a bore of a modulator block2301. The modulator block 2301 may be formed as a rectangular block inwhich not only the simulator valve but also the above-mentionedconstituent elements of the electronic brake system are embeddedcompactly and densely.

The sleeve 2320 may be press-fitted into the valve housing 2310, or iscoupled to the valve housing 2310 by welding. The magnet core 2330 maybe installed at an upper side of the sleeve 2320. The sleeve 2320 mayaccommodate the armature 2350 therein, and may restrict horizontalmovement of the armature 2350 in a manner that the armature 2350 canmove upward and downward only in a longitudinal direction. In this case,the sleeve 1320 may be press-fitted into the valve housing 1310 andcoupled to the valve housing 1310 by welding.

The magnet core 2330 may be press-fitted into the upper side of thesleeve 1320, such that the open upper end of the sleeve 2320 is closed.Although not shown in the drawings, a coupling groove may be formed inthe magnet core 2330, and the magnet core 2330 may be pressed to allowthe sleeve 2320 to be caught in the coupling groove, such that themagnet core 2330 and the sleeve 2320 can be more closely and tightlycoupled to each other. The above-mentioned coupling structure canfacilitate coupling between the sleeve 2320 and the magnet core 2330while simultaneously simplifying a coupling process, as compared to theconventional welding coupling scheme.

The armature 2350 may be installed to move upward and downward in thesleeve 2320, and a ball may be coupled to a lower end of the armature2350 so that the armature 2350 may be in contact with the first valveseat 2360 having an orifice 2360 a. An upper groove of the armature 2350may be arranged to face the magnet core 2330, resulting in formation ofa space in which the first elastic member 2340 is inserted to bedescribed later.

One end of the first elastic member 2340 may be in contact with theupper groove of the armature 2350, and the other end of the firstelastic member 2340 may be in contact with the magnet core 2330. Thefirst elastic member 2340 may apply elastic force to the armature 2350so that the simulator valve 2300 may remain closed in a normal state.When magnetic force does not occur in the magnet core 2330 in a normalstate, the armature 2350 remains pressed downward by the first elasticmember 2340. When the magnet core 2330 produces magnetic force, thearmature 2350 moves upward so that the bidirectional flow passage (0) isopened through the orifice 2360 a.

The first valve seat 2360 may be disposed between the armature 2350 andthe second valve seat 2380, and may include the orifice 2360 a that isopened or closed by the armature 2350 at the lower part of the armature2350. In this case, one end of the second elastic member 2370 may besupported by a curved part of a lower end of the sleeve 2320, and theother end of the second elastic member 2370 may provide elastic force bypressurizing the first valve seat 2360.

The second valve seat 2380 may be fixed to the valve housing 2310, andmay have a unidirectional flow passage (B) that is opened or closed byupward or downward movement of the first valve seat 2360. Here, in theunidirectional flow passage (B), under the condition that pressure ofthe pedal simulator 50 is higher than pressure of the master cylinder20, if the sum of a difference in pressure between the pedal simulator50 and the master cylinder 20 and force generated when the secondelastic member 2370 pushes the armature 2350 is higher than forcegenerated when the first elastic member 2340 pushes the armature 2350,the unidirectional flow passage (B) may be opened.

A filter member 2390 may include a mesh portion provided at the surfacefacing the first port 230A, and may be installed at the outer surface ofthe valve housing 2310. The filter member 2390 may prevent inflow oroutflow of foreign materials contained in the operating fluid flowingthrough the bidirectional or unidirectional flow passage (0 or B).

The simulator valve 2300 including the above-mentioned constituentelements may include the bidirectional flow passage (0) formed when thearmature 2350 moves upward by operation of the magnet core 2360, and theunidirectional flow passage (B) provided between the first valve seat2360 and the second valve seat 2380. In this case, the bidirectionalflow passage (0) may be opened by operation of the magnet core 2360, andthe unidirectional flow passage (B) may be restrictively opened onlywhen pressure of the simulator 50 is higher than pressure of the mastercylinder 20. As a result, when the amount of fluid (or oil) flowing fromthe simulator 50 to the master cylinder 20 is instantaneously increased,the width of the flow passage may be increased in response to theincreased amount of fluid.

FIG. 8 is a side cross-sectional view illustrating an open simulatorvalve according to a fourth embodiment of the present disclosure. FIG. 9is a side cross-sectional view illustrating an open simulator valveaccording to a fourth embodiment of the present disclosure. Referring toFIGS. 8 and 9, the simulator valve 2400 configured to control opening orclosing of a flow passage between the first port 230A and the secondport 230A according to the fourth embodiment may include a sleeve 2420,an armature 2450, a first elastic member 2440, a first valve seat 2460,a second elastic member 2470, and a second valve seat 2480. The sleeve2420 may guide upward or downward movement of the armature 2450, amagnet core 2430 may be fastened to an upper part of the sleeve 2420,and a valve housing 2410 may be fastened to a lower part of the sleeve2420. The armature 2450 may move upward and downward in the sleeve 2420.The first elastic member 2440 may be disposed between the magnet core2430 and the armature 2450, and may provide elastic force to thearmature 2450. The first valve seat 2460 may be located below thearmature 2450, and may have an orifice 2460 a to be opened or closed bythe armature 2450. The second elastic member 2470 may provide the firstvalve seat 2460 with elastic force in the direction of the armature2450. The second valve seat 2480 may be fixed to the valve housing 2410.The unidirectional flow passage (B) may be opened or closed by upward ordownward movement of the first valve seat 2460 disposed between thefirst valve seat 2460 and the second valve seat 2480.

In this case, one end of the second elastic member 2370 may be supportedby an inclined surface of the valve housing 2310, and the other end ofthe second elastic member 2370 may provide elastic force by pressurizingthe first valve seat 2360.

As is apparent from the above description, the electronic brake systemaccording to the embodiments of the present disclosure may efficientlyoperate using a simulator valve provided with a check valve function,and may be easily manufactured at low costs.

Although a few embodiments of the present disclosure have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

What is claimed is:
 1. An electronic brake system comprising: a mastercylinder provided with at least one cylinder chamber having a volumechangeable according to operation of a pedal; a pedal simulatorconnected to the cylinder chamber, configured to provide reaction forcecorresponding to a pedal effort of the pedal; a hydraulic-pressuresupply device configured to provide hydraulic pressure to at least onewheel cylinder; an electronic control unit (ECU) configured to operatethe hydraulic-pressure supply device; and a simulator valve provided ina flow passage through which the master cylinder is connected to thepedal simulator, and provided with a unidirectional flow passage thatallows fluid to flow from the pedal simulator to the cylinder chamberand a bidirectional flow passage that is electronically opened orclosed.
 2. The electronic brake system according to claim 1, wherein theunidirectional flow passage is formed by a lip seal provided in thesimulator valve.
 3. The electronic brake system according to claim 1,wherein the simulator valve includes: a sleeve, an upper part of whichis coupled to a magnet core and a lower part of which is coupled to avalve housing provided with an orifice; an armature configured to moveupward and downward in the sleeve; a first elastic member disposedbetween the magnet core and the armature to provide elastic force to thearmature; and a lip seal coupled to an outer surface of the valvehousing, and provided with an inclined protrusion, wherein theunidirectional flow passage is opened, because the inclined protrusionis deformed inward when pressure of the pedal simulator is higher thanpressure of the master cylinder, and the bidirectional flow passage isopened, because the armature moves by the magnet core receiving acurrent and the orifice is thus opened.
 4. The electronic brake systemaccording to claim 3, wherein the sleeve is press-fitted into an innersurface of the valve housing and is coupled to the valve housing bywelding.
 5. The electronic brake system according to claim 2, whereinthe simulator valve includes: a sleeve, an upper part of which iscoupled to a magnet core and a lower part of which is coupled to the lipseal; an armature configured to move upward and downward in the sleeve;a first elastic member disposed between the magnet core and the armatureto provide elastic force to the armature; and a valve seat disposedbelow the armature, and provided with an orifice to be opened or closedby the armature; and a second elastic member configured to provide thevalve seat with elastic force in a direction of the armature; wherein,when pressure of the pedal simulator is higher than pressure of themaster cylinder, the unidirectional flow passage is opened or closed byupward or downward movement of the valve seat in a space between thevalve seat and the sleeve, or is opened or closed by deformation of aninclined protrusion of the lip seal.
 6. The electronic brake systemaccording to claim 5, wherein: one end of the second elastic member issupported by the sleeve; and the other end of the second elastic memberis configured to pressurize the valve seat at a lower side of the valveseat.
 7. The electronic brake system according to claim 6, wherein thesimulator valve further includes a stopper coupled to a modulator block,wherein the sleeve is press-fitted into an inner surface of the stopperand is coupled to the stopper by welding.
 8. The electronic brake systemaccording to claim 1, wherein the simulator valve includes: a sleeve, anupper part of which is coupled to a magnet core and a lower part ofwhich is coupled to a valve housing; an armature configured to moveupward and downward in the sleeve; a first elastic member disposedbetween the magnet core and the armature to provide elastic force to thearmature; a first valve seat disposed below the armature, and providedwith an orifice to be opened or closed by the armature; a second elasticmember configured to provide the first valve seat with elastic force ina direction of the armature; and a second valve seat fixed to the valvehousing, wherein the unidirectional flow passage is opened or closed byupward or downward movement of the first valve seat in a space betweenthe first valve seat and the second valve seat.
 9. The electronic brakesystem according to claim 8, wherein: one end of the second elasticmember is supported by the sleeve; and the other end of the secondelastic member is configured to pressurize the first valve seat at alower side of the first valve seat.
 10. The electronic brake systemaccording to claim 8, wherein: one end of the second elastic member issupported by the valve housing; and the other end of the second elasticmember is configured to pressurize the first valve seat at a lower sideof the first valve seat.
 11. The electronic brake system according toclaim 8, wherein: the first elastic member allows the second elasticmember to have stronger force than force needed to pressurize the firstvalve seat such that the orifice remains closed in a normal state; andwhen a current is supplied to the magnet core, the armature moves andthe orifice is thus opened.
 12. The electronic brake system according toclaim 8, wherein: in case that pressure of the pedal simulator is higherthan pressure of the master cylinder, if a sum of a difference inpressure between the pedal simulator and the master cylinder and forcegenerated when the second elastic member pushes the first valve seat ishigher than other force generated when the first elastic member pushesthe first valve seat, the unidirectional flow passage is opened.
 13. Asimulator valve comprising: a sleeve, an upper part of which is fastenedto a magnet core and a lower part of which is fastened to a valvehousing provided with an orifice; an armature configured to move upwardand downward in the sleeve; a first elastic member disposed between themagnet core and the armature so as to provide elastic force to thearmature; a lip seal fastened to an outer surface of the valve housing,and provided with an inclined protrusion; a unidirectional flow passageprovided with an inclined protrusion, wherein the inclined protrusion isdeformed inward when pressure of a pedal simulator is higher thanpressure of a master cylinder such that the unidirectional flow passageis opened; and a bidirectional flow passage configured to open theorifice by movement of the armature after a current is supplied to themagnet core.
 14. The simulator valve according to claim 13, wherein thesleeve is press-fitted into the valve housing and is coupled to thevalve housing by welding.
 15. A simulator valve comprising: a sleeve, anupper part of which is fastened to a magnet core and a lower part ofwhich is fastened to a lip seal provided with an inclined protrusion; anarmature configured to move upward and downward in the sleeve; a firstelastic member disposed between the magnet core and the armature so asto provide elastic force to the armature; a valve seat located below thearmature, and provided with an orifice to be opened or closed by thearmature; a second elastic member configured to provide the valve seatwith elastic force in the direction of the armature; and aunidirectional flow passage, when pressure of the pedal simulator ishigher than pressure of the master cylinder, that is opened or closed byupward or downward movement of the valve seat in a space between thevalve seat and the sleeve or is opened or closed by deformation of theinclined protrusion of the lip seal.
 16. The simulator valve accordingto claim 15, wherein: one end of the second elastic member is supportedby the sleeve; and the other end of the second elastic member isconfigured to pressurize the valve seat at a lower side of the valveseat.
 17. The simulator valve according to claim 16, wherein thesimulator valve further includes a stopper coupled to a modulator block,wherein the sleeve is press-fitted into an inner surface of the stopperand is coupled to the stopper by welding.
 18. A simulator valvecomprising: a sleeve, an upper part of which is coupled to a magnet coreand a lower part of which is coupled to a valve housing; an armatureconfigured to move upward and downward in the sleeve; a first elasticmember disposed between the magnet core and the armature to provideelastic force to the armature; a first valve seat disposed below thearmature, and provided with an orifice to be opened or closed by thearmature; a second elastic member configured to provide the first valveseat with elastic force in a direction of the armature; and a secondvalve seat fixed to the valve housing, wherein the unidirectional flowpassage is opened or closed by upward or downward movement of the firstvalve seat in a space between the first valve seat and the second valveseat.
 19. The simulator valve according to claim 18, wherein: one end ofthe second elastic member is supported by the sleeve; and the other endof the second elastic member is configured to pressurize the first valveseat at a lower side of the first valve seat.
 20. The simulator valveaccording to claim 18, wherein: one end of the second elastic member issupported by the valve housing; and the other end of the second elasticmember is configured to pressurize the first valve seat at a lower sideof the first valve seat.
 21. The simulator valve according to claim 18,wherein: the first elastic member allows the second elastic member tohave stronger force than force needed to pressurize the first valve seatsuch that the orifice remains closed in a normal state; and when acurrent is supplied to the magnet core, the armature moves and theorifice is thus opened.
 22. The simulator valve according to claim 18,wherein: in case that pressure of the pedal simulator is higher thanpressure of the master cylinder, if a sum of a difference in pressurebetween the pedal simulator and the master cylinder and force generatedwhen the second elastic member pushes the first valve seat is higherthan other force generated when the first elastic member pushes thefirst valve seat, the unidirectional flow passage is opened.